Oxidative processes in glomerulonephritides: additional facts

C-reactive protein induces NF-kappaB activation through intracellular calcium and ROS in human mesangial cells

BACKGROUND

C-reactive protein (CRP) is known to have a direct proinflammatory effect in endothelial cells. However, little is known about the effect of CRP in intrinsic renal cells. We investigated the effects of CRP on the nuclear factor-kappaB (NF-kappaB) activation and monocyte chemoattractant protein-1 (MCP-1) gene expression in human mesangial cells and also examined whether intracellular calcium and reactive oxygen species (ROS) were involved in the CRP- induced NF-kappaB activation.

METHODS

NF-kappaB binding activity and MCP-1 mRNA expression were measured by electrophoretic mobility shift assay and Northern blot analysis, respectively. Intracellular calcium was monitored by confocal microscopy using calcium sensitive dye, Fluo-3 and intracellular ROS production was determined, using 2',7'-dichlorofluorescin diacetate.

RESULTS

CRP increased NF-kappaB binding activity in a dose-dependent manner (12.5-100 microg/ml), which was induced within 1 h after incubation and peaked around 3 h. CRP also increased the MCP-1 mRNA expression via activation of NF-kappaB. Both intracellular calcium and ROS was induced by CRP. Calcium chelator, BAPTA-AM and anti-oxidants such as N-acetylcysteine and tiron suppressed CRP-induced NF-kappaB activation.

CONCLUSION

CRP exerted a proinflammatory effect in human mesangial cells by inducing MCP-1 gene expression via NF-kappaB activation, which was mediated, at least in part, through intracellular calcium and ROS.

Tubular CD146 Expression in Nephropathies Is Related to Chronic Renal Failure

BACKGROUND

CD146, a member of the immunoglobulin superfamily, is mainly expressed at the endothelial junction. The soluble form of CD146 is increased in the serum of patients with chronic renal failure. The aim of the study was to investigate CD146 expression on biopsies of normal kidney and nephropathies.

METHODS

We did an immunohistochemical analysis of 10 normal renal tissues and 126 patients with nephropathies.

RESULTS

The mean age of the patients was 47.5 +/- 18 years with 65% of men. At the time of the biopsy, 73 patients (57.9%) had a renal failure and the mean proteinuria was 3.3 +/- 2.9 g/24 h. Inflammatory syndrome was present in 60 (47.6%) patients. Fibrous interstitial changes from minimal lesions to diffuse lesions were seen in 105 (83.3%) biopsies; the mean glomerulosclerosis index was 16.9 +/- 19.7%. Normal kidneys showed CD146 staining on endothelial cells, smooth muscle cells, and mesangium. Normal tubular cells were not stained. If endocapillary proliferation was present, the mesangial CD146 expression was higher. This mesangial expression correlated with proteinuria (p = 0.007) and not with renal failure (p = 0.07). A de novo expression on tubular cells was found in 53 patients (42%) and this expression correlated with age (p < 0.001), male sex (p = 0.04), glomerulosclerosis (p < 0.001), interstitial fibrosis (p < 0.001), and renal failure (p < 0.001).

CONCLUSION

Renal CD146 expression is of interest for determining the pathogenesis of mesangial alterations during glomerular injuries and of tubular phenotypic changes during chronic renal failure.

[Pharmacological study on the effects of the adenosine uptake inhibitor KF24345 on inflammatory diseases]

Adenosine protects against cellular damage and dysfunction under several adverse conditions, including inflammation. We examined the effects of KF24345, a novel adenosine uptake inhibitor, on inflammatory diseases to investigate whether the adenosine uptake inhibition is useful for the treatment of inflammation. KF24345 inhibited adenosine uptake into washed erythrocytes (in vitro) and sampled blood cells from mice after its oral administration (in vivo). KF24345 significantly suppressed lipopolysaccharide-induced tumor necrosis factor-alpha production and leukopenia in mice, and the effects of KF24345 were abolished by the treatment with a non-selective or an A(2A)-selective adenosine receptor antagonist. In the experimental glomerulonephritis induced in mice by anti-glomerular basement membrane antiserum, KF24345 significantly inhibited proteinuria and glomerular damage without exhibiting the side effects observed following the treatment with prednisolone and cyclophosphamide. In addition, KF24345 ameliorated the severity of experimental acute pancreatitis induced by cerulein or choline-deficient and ethionine-supplemented diet in mice, and it decreased mortality accompanying severe acute pancreatitis. The anti-pancreatitis effects of KF24345 were abolished by the treatment with a non-selective or an A(2A)-selective adenosine receptor antagonist. These results suggest that KF24345 and adenosine uptake inhibitors can be a new therapeutic approach for various inflammatory diseases, including glomerulonephritis and acute pancreatitis.

Oxidative stress and hemodynamic maladjustment in chronic renal disease: a therapeutic implication

Hemodynamic maladjustment with predominant constriction at the efferent arteriole has been encountered in a variety of clinical settings of glomerulonephropathy. In essence, it induces not only intraglomerular hypertension but also exaggeratedly reduces the peritubular capillary flow, which supplies the tubulointerstitial compartment. The hemodynamic maladjustment is believed to reflect a glomerular endothelial cell dysfunction. In this regard, oxidative stress and antioxidant defect are likely responsible for the glomerular endothelial dysfunction. Improvement in renal function was accomplished following the correction of oxidant and antioxidant imbalance with antioxidant therapy and vasodilators. Following such therapy, there was a correction in hemodynamic maladjustment with a decline in intraglomerular hydrostatic pressure and an increase in renal perfusion with a subsequent increase in renal functions namely creatinine clearance, glomerular filtration rate and a decline in FEMg.

Inhibition of c-Jun N-terminal kinase ameliorates apoptosis induced by hydrogen peroxide in the kidney tubule epithelial cells (NRK-52E)

BACKGROUND

Hydrogen peroxide (H2O2)-induced apoptosis has been shown to be involved in ischemic and toxic tubular damage. Recent studies have revealed that oxidative stress can activate c-Jun N-terminal kinase (JNK), and the oxidative stress-JNK pathway is an important apoptotic pathway of cells exposed to various stresses. The present study was designed to investigate JNK activation and the effects of the JNK pathway inhibition during H2O2-induced apoptosis in kidney epithelial tubule cells (NRK-52E).

MATERIALS AND METHODS

NRK-52E cells were treated with 0-500 microM H2O2 and/or 100 microM quercetin (an inhibitor of the JNK pathway). Apoptosis was assessed by flow cytometry analysis and DNA ladder. JNK activity was assessed by the GST-c-Jun (1-169) binding/protein kinase assay.

RESULTS

H2O2 induced apoptosis in NRK-52E cells in a concentration-dependent manner, which was demonstrated by the reduced DNA PI staining, externalization of phosphatidylserine and DNA ladder. Apoptosis induced by H2O2 was accompanied by JNK activation and up-regulated JNK activity. Quercetin treatment suppressed the JNK activity and ameliorated apoptosis induced by H2O2.

CONCLUSIONS

H2O2 induced apoptosis in NRK-52E cells, which was associated with activation and up-regulation of JNK. Quercetin treatment could decrease JNK activity and ameliorate H2O2-induced apoptosis.